Acid anhydride treatment of wool in the presence of cresol



United States Patent C) 3,332,733 ACID ANHYDRIDE TREATMENT OF WOOL IN THE PRESENCE OF CRESOL Nathan H. Koenig, Berkeley, Calif., assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 13, 1964, Ser. No. 389,503 8 Claims. (Cl. 8-128) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates broadly to the chemical modification of wool by reacting it with an organic acid anhydride. In particular, the invention concerns and has as its prime object the provision of processes wherein the reaction of wool with organic acid anhydrides is conducted in the presence of cresol, whereby to facilitate and promote the reaction. The unqualified term cresol used herein includes o-cresol, m-cresol, p-cresol, or any mixture of these isomers. Further objects and advantages of the invention will be apparent from the following description wherein parts and percentages are by weight, unless otherwise specified.

Although wool is a very useful fiber, it is often desirable to improve its properties for particular applications by chemically modifying it. In accordance with the present invention, wool is reacted with an acid anhydride in the presence of cresol. The latter compound catalyzes the actual chemical combination of the wool and the acid anhydride reactant. As a consequence one is enabled to readily prepare wools containing substantial proportions of combined acid anhydride with correspondingly improved properties.

The unusual and eflective action of cresol as a catalyst for the reaction in questinrather than as a mere solventis demonstrated by the following experimental data:

Example 1 (a) Dry wool flannel (1.2 g.) and dodecenylsuccinic anhydride ml.) were heated for 90 minutes at 105 C. The wool was then extracted with acetone and ethanol to remove unreacted reagents and dried. It was found that the increase in weight of the wool was only 1%.

(b) Dry wool flannel (1.2 g.) was heated with p-cresol (5 ml.) at 105 C. for 30 minutes. The wool was extracted as described in Part (a) and dried. The increase in weight of the wool was only 2%.

(c) Dry wool flannel (1.2 g.) was heated with dodecenylsuccinic anhydride (2 ml.) and p-cresol (4 ml.) at 105 C. for 30 minutes. The wool was extracted as described in Part (a) and dried. In this case the increase in weight of the wool, due to reaction with the anhydride, was 14%.

Example) (a) Dry wool flannel 1.2 g.), dodecenylsuc-cinic anhydride (2 ml.), and p-cresol (4 ml.) were heated for one hour at 105 C. The wool was extracted with acetone and ethanol to remove unreacted reagents and dried. It was found that the increase in weight of the wool, due to reaction with the anhydride, was 21%.

(b) A series of experiments were then carried out under the same conditions but substituting for the p-cresol the same volume of the following solvents: butyl acetate, butyl ether, chlorobenzene, methyl isobutyl ketone, and xylene. In these runs, the increase in weight of the wool was only 0 to 1%.

Carrying out the process of the invention essentially involves contacting wool with an acid anhydride in the presence of cresol. The reaction conditions such as proportion of reagents, specific acid anhydride used, time, temperature, etc., are not critical but may be varied to suit individual circumstances without changing the basic nature of the invention. The be varied widely and may be as low as 0.1 volume per volume of acid anhydride. In the case of acid anhydrides which are normally solid, the volume considered is that of the molten (liquefied) compound. Usually, it is preferred to use a larger proportion of cresol, i.e., about 1 to 10 volumes thereof per volume of acid anhydride, to attain an increased catalytic effect. The temperature of reaction may be about from 50 to 130 C. The reaction rate is increased with increasing temperature and a preferred temperature range to expedite the reaction without damage to the wool is -120 C.

Conventional inert solvents such as chlorobenzene, xylene, or butyl acetate may be added to the reaction system. The use of a solvent is especially indicated where the acid anhydride used is a solid and the proportion of cresol is not sufiicient to dissolve the acid anhydride. It

is preferred to carry out the reaction under anhydrous conditions thereby to ensure reaction between the wool and the acid anhydride, but the reaction can also be applied to wool in its normal undried condition (containing about 1214% water). The degree of modification of the Wool is related to the proportion of acid anhydride taken up by the fiber, that is, the higher the uptake of acid anhydride the greater will be the modification of the wool. In general, the uptake of acid anhydride may be varied about from 1 to 30 by weight. In conducting the reaction, the acid anhydride is generally employed in excess over the amount desired to be taken up by the fiber. The time of reaction will vary depending on the proportion of cresol, temperature of reaction, reactivity of the acid anhydride selected, and the degree of modification desired. In general, the reaction may take anywhere from a few minutes to several hours.

The process in accordance with the invention may be carried out in various ways. For example, the wool may be directly contacted with the cresol and acid anhydride reactant and the reaction mixture preferably heated as indicated above to cause the acid anhydride to react with the Wool. In the alternative, the wool may be pretreated with cresol and the acid anhydride then added to the mixture and the reaction carried out as previously described. The pretreatment may be carried out at normal temperature or with application of heat, i.e., at 25130 C.

After reaction of the wool with the acid anhydride, the chemically modified wool is preferably treated to remove excess acid anhydride, reaction lay-products, cresol, and solvent, if such is used. Thus, the wool may be treated as by wringing, passage through squeeze-rolls, centrifugation, or the like, to remove the excess materials. In place of such mechanical action, or following it, the product may be extracted with an inert, volatile solvent such as trichloroethylene, benzene, acetone, carbon tetrachloride, alcohol, etc. Successive extractions with different solvents may be used to ensure complete removal of all unreacted materials. The treated wool is then dried in the usual way.

By treating wool with acid anhydrides as herein described, the wool is chemically modified because there is a chemical reaction between the acid anhydride and the protein molecules of the wool fibers. As a result the modified wool exhibits advantageous properties over normal wool as explained below:

An advantageous feature of the invention is the increased resistance of the modified wool to acids as indicated by its decreased solubility in hot hydrochloric acid. This factor improves the usefulness of the modified woo] proportion of cresol may in applications where. the product comes into contact with acidic materials. For example, wool may encounter acid conditions during manufacturing processes such as carbonizing to remove burrs; dyeing in acid dye baths; and fulling with acid media. The more resistant the wool is to such acid environments, the greater will be its subsequent mechanical strength and wear resistance.

The tendency of wool to shrink when subjected to washing in aqueous media has long been a deterrent to the more widespread use of wool. An important advantage of the invention is that it yields modified wools which have a decreased tendency to shrink when subjected to washing with conventional soap and water or detergent and water formulations.

Although the properties of the modified wool indicate beyond question that actual chemical combination between the wool and the acid anhydride has taken place, it is not known for certain how the wool. and acid anh dride moieties are joined. It is believed, however, that the acid anhydride reacts with some of the sites on the wool molecule where there are reactive hydrogen atoms, e.g., amino, guanidino, hydroxyl, and phenolic groups. It may be, however, that other reactions occur and it is not intended to limit the invention to any theoretical basis. When the reaction is carried out with polybasic acid anhydrides, for example, pyromellitic dianhydride, combination with the wool may establish cross-links between protein molecules of the wool that further increase the resistance of the fibers to chemical attack.

It is to be noted that the reaction in accordance with the invention does not impair the wool fiber for its intended purpose, that is, for producing woven or knitted textiles, garments, etc. The process of the invention may be applied to wool in the form of fibers, as such, or in the form of threads, yarns, slivers, rovings, knitted or woven goods, felts, etc. The wool textiles may be white or dyed goods and may be of all-wool composition or blends of wool with other textile fibers such as cotton, regenerated cellulose, viscose, animal hair, etc.

The invention is of particular advantage in reacting wool with acid anhydrides of higher molecular weightthat is, those with more than eight carbon atoms. Such anhydrides are notorious for their inability to react with wool in absence of a catalyst. However, by applying the process disclosed herein such anhydrides can be caused to react readily with wool.

Although the invention is particularly adapted for reacting wool with acid anhydrides'containing more than eight carbon atoms, the catalytic effect of cresol is not restricted to any articular acid anhydride or class of acid anhydrides. Consequently, the invention may be applied in the reaction of wool with all types of organic acid anhydrides. Particularly preferred are the aliphatic, aromatic, and aromatic-aliphatic compounds containing one or more of the characteristic anhydride linkages, that is, the group The anhydrides may be hydrocarbon acid anhydrides or may contain substituents on the hydrocarbon residues such as halogen (chlorine, bromine, iodine, or fluorine), ether groups, ester groups, nitro groups, carboxy groups, etc. Examples of compounds coming within the purview of the invention are listed below-by way of illustration and not limitation:

Typical examples of compounds in the cataegory of aliphatic acid anhydrides are acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, isovaleric anhydride, trimethylacetic anhydride, caproic anhydride, caprylic anhydride, capric anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, arachidic anhydride, crotonic anhydride, angelic anhydride, oleic anhydride, elaidic anhydride, linoleic anhydride, linolenic anhydride, maleic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, suberic anhydride, azelaic anhydride, sebacic anhydride, heptylsuccinic anhydride, octylsuccinic anhydride, decylsuccinic anhydride, dodecylsuccinic anhydride, heptenylsuccinic anhydride, octenylsuccinic anhydride, dodecenylsuccinic anhydride, tetrapropenylsuccinic anhydride, octadecenylsuccinic anhydride, tricosenylsuccinic anhydride, pentatriacontenylsuccinic anhydride, chloroacetic anhydride, bromoacetic anhydride, iodoacetic anhydride, fiuoroa-cetic anhydride, 9, 10-dichloro octadecanoic anhydride, ethoxyacetic anhydride, carbethoxyacetic anhydride, afi-dichlorosuccinic anhydride, cyclohexanecarboxylic anhydride, hexahydrophthalic anhydride, etc. Of the aliphatic acid anhydrides, it is preferred to use the anhydrides which contain at least eight carbon atoms. These compounds are preferred as they confer on the treated wool especially desirable properties including resistance to acids and shrinkage.

Typical examples in the category of aromatic acid an hydrides are benzoic anhydride, ortho-toluic anhydride, meta-toluic anhydride, paratoluic anhydride, naphthoic anhydride, dodecylbenzoic anhydride, ortho-chlorobenzoic anhydride, meta-chlorobenzoic anhydride, parachlorobenzoic anhydride, 2,4-dichlorobenzoic anhydride, nitrobenzoic anhydride, phthalic anhydride, terephthalic anhydride, tetrachlorophthalic anhydride, pyrornellitic dianhydride, etc.

Typical examples in the category of aromatic-aliphatic anhydrides are phenylacetic anhydride, chlorophenylacetic anhydride, fi-phenylpropionic anhydride, phenoxyacetic anhydride, etc.

Any of the mixed anhydrides may be employed, for example, acetic-lauric anhydride, acetic-stearic anhydride, acetic-oleic anhydride, propionic-palmitic anhydride, acetic-butyric anhydride, acetic-benzoic anhydride, benzoicstearic anhydride, acetic-naphthenic anhydride, di-aceticsuccinic anhydride, di-acetic-dodecenylsuccinic anhydride, etc.

The invention is demonstrated by Examples 1 and 2, above, and by the following examples:

Example 3 A series of runs was carried out wherein dry wool flannel was reacted with various anhydrides in the presence of m-cresol. In these runs, the weight of dry wool Was 1.2 grams, the volume of anhydride was 2 ml., the volume of m-cresol was 4 ml., and the temperature of reaction was C. The treated wool samples were extracted by rinsing and wringing in warm acetone. They were then extracted with ethanol for 16 hours in a Soxhlet apparatus, dried and weighed. The uptakes of anhydride were calculated from the weight gain.

The anhydrides used, the reaction time, and the uptakes of anhydride are tabulated below:

The acid solubility of modified wools produced in accordance with the invention and that of untreated wool were determined in the following way: The wool sample is immersed in 5 N hydrochloric acid for one hour at 65 C. The loss in weight of the sample is then determined after thoroughly washing the acid-soaked wool.

The increased resistance of modified wools to hot hydrochloric acid is illustrated by the following data:

Uptake of Anhydride Acid soluanhydnde by wool, percent blhty percent None (untreated wool) 12 Octenylsuccinic 23 3 Dodecenylsuccinic 18 2 ll-tricosenylsuccinie 18 1 Example 5 wherein R is an alkenyl radical. More specifically, the radical R in the various compounds is as follows:

Octenylsuccinic anhydride: R is C H Dodecenylsuccinic anhydride: R is C H Octadecenylsuccinic anhydride: R is C H ll-tricosenylsuccinic anhydride: R is C H Having thus defined the invention, what I claim is:

1. A process for chemically modifying wool which comprises reacting wool under essentially anhydrous conditions, in the presence of cresol, with an acid anhydride of the class consisting of aliphatic, aromatic, and aromaticaliphatic acid anhydrides.

2. The process of claim 1 wherein the acid anhydride is an aliphatic mono-basic acid anhydride containing at least eight carbon atoms.

3. The process of claim 1 wherein the acid anhydride is hexahydrophthalic anhydride.

4. The process of claim 1 wherein the acid anhydride is an alkenylsuccinic anhydride of the formulawool modified in accordance with the invention is demonstrated by the following data: R-CHC CH:C/ Uptake of Area shrink- Anhydride anhydride by age, percent 0 W001, percent wherein R is an alkenyl radical of at least seven carbon None (untreated wool) 0 49 atomsgg g g ggggfi fi if 3 5. The process of claim 4 wherein R is octenyl.

""""""""" 6. The process of claim 4 wherein R is dodecenyl.

7. The process of claim 4 wherein R is octadecenyl. 8. The process of claim 4 wherein R is tricoscnyl.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner.

I. C. CANNON, Assistant Examiner. 

1. A PROCESS FOR CHEMICALLY MODIFYING WOOL WHICH COMPRISES REACTING WOOL UNDER ESSENTIALLY ANHYDROUS CONDITIONS, IN THE PRESENCE OF CRESOL, WITH AN ACID ANHYDRIDE OF THE CLASS CONSISTING OF ALIPHATIC, AROMATIC, AND AROMATICALIPHATIC ACID ANHYDRIDES. 